Quad-redundant hydraulic trip system

Abstract

A voting solenoid system and method is configured to selectively apply fluid pressure above and below a threshold value, to a fluid node. The voting solenoid arrangement includes first and second solenoid valve pairs, each pair including first and second solenoid valves. The valve pairs are located in parallel fluid communication with a fluid pressure source, each of the first and second solenoid valves being alternately actuatable between energized and de-energized states. The solenoid arrangement is configured so that a change of state of the first and second valves of either of the valve pairs alternately applies fluid pressure above and below the threshold value, to the fluid node.

Having thus described the invention, what is claimed is: 
     
       1. A voting solenoid arrangement configured to selectively apply fluid pressure above and below a threshold value, to a fluid node, said voting solenoid arrangement comprising:
 first and second solenoid valve pairs, each pair including first and second solenoid valves; 
 said valve pairs being disposed in parallel fluid communication with a fluid pressure source; 
 each of said first and second solenoid valves being alternately actuatable between energized and de-energized states; 
 wherein a change of state of the first and second valves of either of said valve pairs is configured to alternately apply fluid pressure above and below the threshold value, to the fluid node. 
 
     
     
       2. The voting solenoid arrangement of  claim 1 , wherein said valve pairs are selectively disposed in parallel fluid communication with a low pressure fluid reservoir, said low pressure being below the threshold value. 
     
     
       3. The voting solenoid arrangement of  claim 2 , wherein said fluid pressure source comprises said fluid node. 
     
     
       4. The voting solenoid arrangement of  claim 3 , wherein each of said valve pairs comprises a pair of pilot valves disposed in fluid communication therewith. 
     
     
       5. The voting solenoid arrangement of  claim 4 , comprising a test solenoid valve disposed for fluid communication between the fluid node and each of said valve pairs. 
     
     
       6. The voting solenoid arrangement of  claim 1 , wherein said first and second solenoid valves of said valve pairs each comprise four port, two position solenoid valves. 
     
     
       7. The voting solenoid arrangement of  claim 6 , wherein said four port, two position solenoid valves comprise a pair of common ports which are selectively couplable in fluid communication to one another, and to two other ports, said alternate actuation including alternately coupling said pair of common ports to one another, and to a mutually distinct one of said two other ports. 
     
     
       8. The voting solenoid arrangement of  claim 1 , wherein:
 said first and second solenoid valves are each coupled in fluid communication with a fluid supply; 
 said first and second solenoid valves of each valve pair are disposed in fluid communication with one another; and 
 said second solenoid valves are each coupled in fluid communication with said fluid node. 
 
     
     
       9. The voting solenoid arrangement of  claim 8 , wherein:
 each of said first and second solenoid valves comprise a plurality of upstream ports and a plurality of downstream ports; 
 the fluid supply is coupled to an upstream one of said common ports of each of said first and second solenoid valves; 
 the fluid node is couple to a downstream one of said common ports of said second solenoid valves; 
 the low pressure reservoir is coupled to a downstream one of said other ports of said first and second solenoid valves, and to an upstream one of said other ports of said first solenoid valves; and 
 a downstream one of said common ports of said first solenoid valves being respectively coupled to an upstream one of said other ports of said second solenoid valves. 
 
     
     
       10. The voting solenoid arrangement of  claim 1 , further comprising a plurality of shut-off valves configured to selectively isolate either one of said valve pairs from the fluid node, wherein the applied pressure is maintained by the other of said valve pairs. 
     
     
       11. The voting solenoid arrangement of  claim 10 , wherein when one of said valve pairs is isolated, a change of state of the first and second valves of the other of said valve pairs is configured to alternately apply fluid pressure above and below the threshold value, to the fluid node. 
     
     
       12. The voting solenoid arrangement of  claim 1 , wherein the fluid comprises hydraulic fluid. 
     
     
       13. The voting solenoid arrangement of  claim 1 , wherein the applied fluid pressure is above the threshold pressure when said first and second solenoid valves of either of said valve pairs are disposed in said energized state. 
     
     
       14. The voting solenoid arrangement of  claim 13 , wherein any one of said first and second solenoid valves of said first and second valve pairs is configured for being disposed in said de-energized state without dropping the applied fluid pressure below the threshold pressure. 
     
     
       15. The voting solenoid arrangement of  claim 1 , further comprising a plurality of pressure sensors operatively associated with one or more of said first and second solenoid valves to indicate the state thereof. 
     
     
       16. The voting solenoid arrangement of  claim 15 , wherein said plurality of pressure sensors is configured to indicate the state of each of said first and second solenoid valves. 
     
     
       17. The voting solenoid arrangement of  claim 15 , wherein said first and second solenoid valves are configured for being individually tested without dropping the applied fluid pressure below the threshold pressure. 
     
     
       18. A method for selectively applying fluid pressure above and below a threshold value to a fluid node, the method comprising:
 providing first and second solenoid valve pairs, each pair including first and second solenoid valves; 
 said first and second solenoid valves being alternately actuatable between energized and de-energized states; 
 disposing said valve pairs in parallel fluid communication with a fluid pressure source; 
 disposing the first and second solenoid valves in fluid communication with one another wherein a change of state of the first and second solenoid valves of either of said valve pairs is configured to alternately apply fluid pressure above and below the threshold value, to the fluid node. 
 
     
     
       19. A voting solenoid arrangement configured to selectively apply fluid pressure above and below a threshold value, to a fluid node, said voting solenoid arrangement comprising:
 first and second solenoid valve pairs, each pair including first and second solenoid valves; 
 said valve pairs being disposed in parallel fluid communication with a fluid pressure source; 
 each of said first and second solenoid valves being alternately actuatable between energized and de-energized states; 
 wherein a change of state of the first and second valves of either of said valve pairs is configured to alternately apply fluid pressure above and below the threshold value, to the fluid node; 
 said valve pairs being selectively disposed in parallel fluid communication with a low pressure fluid reservoir, said low pressure being below the threshold value; 
 a plurality of shut-off valves configured to selectively isolate either one of said valve pairs from the fluid node, wherein the applied pressure is maintained by the other of said valve pairs; 
 a plurality of pressure sensors operatively associated with one or more of said first and second solenoid valves to indicate the state thereof; and 
 the applied fluid pressure configured to be above the threshold pressure when said first and second solenoid valves of either of said valve pairs are disposed in said energized state.